Polymorphisms in Plasmodium vivax Circumsporozoite Protein (CSP) Influence Parasite Burden and Cytokine Balance in a Pre-Amazon Endemic Area from Brazil

PLoS Negl Trop Dis. 2016 Mar 4;10(3):e0004479. doi: 10.1371/journal.pntd.0004479. eCollection 2016 Mar.

Abstract

Mechanisms involved in severe P. vivax malaria remain unclear. Parasite polymorphisms, parasite load and host cytokine profile may influence the course of infection. In this study, we investigated the influence of circumsporozoite protein (CSP) polymorphisms on parasite load and cytokine profile in patients with vivax malaria. A cross-sectional study was carried out in three cities: São Luís, Cedral and Buriticupu, Maranhão state, Brazil, areas of high prevalence of P. vivax. Interleukin (IL)-2, IL-4, IL-10, IL-6, IL-17, tumor necrosis factor alpha (TNF-α, interferon gamma (IFN-γ and transforming growth factor beta (TGF-β were quantified in blood plasma of patients and in supernatants from peripheral blood mononuclear cell (PBMC) cultures. Furthermore, the levels of cytokines and parasite load were correlated with VK210, VK247 and P. vivax-like CSP variants. Patients infected with P. vivax showed increased IL-10 and IL-6 levels, which correlated with the parasite load, however, in multiple comparisons, only IL-10 kept this association. A regulatory cytokine profile prevailed in plasma, while an inflammatory profile prevailed in PBMC culture supernatants and these patterns were related to CSP polymorphisms. VK247 infected patients showed higher parasitaemia and IL-6 concentrations, which were not associated to IL-10 anti-inflammatory effect. By contrast, in VK210 patients, these two cytokines showed a strong positive correlation and the parasite load was lower. Patients with the VK210 variant showed a regulatory cytokine profile in plasma, while those infected with the VK247 variant have a predominantly inflammatory cytokine profile and higher parasite loads, which altogether may result in more complications in infection. In conclusion, we propose that CSP polymorphisms is associated to the increase of non-regulated inflammatory immune responses, which in turn may be associated with the outcome of infection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Animals
  • Brazil / epidemiology
  • Cells, Cultured
  • Child
  • Child, Preschool
  • Cities / epidemiology
  • Cross-Sectional Studies
  • Cytokines / blood*
  • Female
  • Genetic Variation*
  • Humans
  • Leukocytes, Mononuclear / immunology
  • Malaria, Vivax / epidemiology*
  • Malaria, Vivax / parasitology
  • Malaria, Vivax / pathology*
  • Male
  • Middle Aged
  • Parasite Load*
  • Plasmodium vivax / genetics*
  • Plasmodium vivax / isolation & purification
  • Protozoan Proteins / genetics*
  • Young Adult

Substances

  • Cytokines
  • Protozoan Proteins
  • circumsporozoite protein, Protozoan

Grants and funding

This work was funded by: Fundação de Amparo à Pesquisa do Estado do Maranhão- Grant number: 01598/09; www.fapema.br to FRFN; Conselho Nacional de Desenvolvimento Científico e Tecnológico- Grant number: 302129/2012-0; www.cnpq.br to FRFN; Conselho Nacional de Desenvolvimento Científico e Tecnológico- Grant number: 134159/2011-0; www.cnpq.br to BPdR; and Fundação de Apoio à Pesquisa do Estado de São Paulo- Grant number: 2009/53889-0; www.fapesp.br to CRFM. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.